The invention is directed to a process and a device for power- and air conditioning-fresh air generation in aircraft, which are equipped with main power plants and an auxiliary power unit driving an air conditioning compressor with an appropriate air intake, compressor, diffuser and an associated exhaust nozzle as well as a heat exchanger and which comprise a suction device for removing the boundary layer from aircraft wings.
The installation of an auxiliary power unit in the tail of aircraft for generation of electrical current and for the supply of air conditioned ambient air to the aircraft is known, whereby the auxiliary power unit assumes this task only during the periods, when the aircraft is on the ground during loading and unloading and during fueling and while the main power plants are not in operation. According to existing practice, the auxiliary power unit is shut down in flight and the main power units assume the task of power and fresh air supply.
From DE-OS No. 31 21 909 for instance an integrated auxiliary power and air conditioning unit has become known, which has a variable geometry compressor, which can be driven on the one hand by bleed air from the main power plant and on the other hand through a freewheeling clutch by the auxiliary power unit for power- and air conditioning-fresh air supply.
The device has the disadvantage that for its operation a high fuel consumption is required, because without additional power supply this is always proportional to the output, which the main power plants must generate for the required bleed air amount or the auxiliary power unit must supply as mechanical output for the pertinent supply functions of the aircraft. Apart from that the compressor stages of the main power plants are primarily optimized for the generation of forward thrust and not for the production of bleed air, whereby for this additional air mass the entire main power plant has to be designed to be larger. Over and above that the main power plants are very highly loaded by the removal of bleed air, particularly during the take-off phase and thus the flight safety of the aircraft is jeopardized.